The present invention relates to a mechanical switch in which a plurality of electric conductors is mechanically contacted and separated by a pressure force. More particularly, the present invention pertains to a pressure-sensing switch configured as a sheet (i.e., flexible thin plate), which binary detects the existence of an object including an occupant on a seat.
A known pressure-sensing switch is disclosed in Japanese Patent Laid-Open Publication No. H10-206254. As shown in FIG. 6, a pressure-sensing switch A includes a pressure detection member A1 and a film A2 for wrapping the pressure detection member A1. The pressure sensing switch A includes two pressure sensing members A3 which are arranged in a width direction (i.e., right, left direction of FIG. 6) and two connection members A4 provided for connecting the pressure sensing members A3, A3 each other. Each connection member A4 includes a U-shape portion A5 and a connection portion A6 extended from the U-shape portion A5 whose curve portion faces downward of FIG. 6 to be connected to the pressure-sensing member A3.
Provided that the pressure-sensing switch A is positioned as shown in FIG. 7 relative to a seat cushion A8 of the seat. The pressure-sensing switch A is provided under a cover (not shown) of the seat cushion A8. A portion of the pressure-sensing switch A (e.g., leg portion A7) is fixed to a cushion member A9 in the seat cushion A8 with a bonding agent. When a person sits on the seat cushion A8 or when an object is placed on the seat cushion A8, a central portion of a top surface of the cushion member A9 goes down to be deformed in perpendicular perspective direction of FIG. 7. In this case, the tension force is applied to the pressure-sensing switch A in its width direction (i.e., right, left direction of FIG. 7). The connection member A4 absorbs the tension force by deforming in the direction that the U-shape portion A5 is extended. FIG. 8a shows a normal configuration of the U-shape portion A5. FIG. 8b shows the configuration of the U-shape portion A5 under the stretched condition.
Notwithstanding, in this case, because the U-shape portion A5 is deformed in the direction to be stretched, there is a drawback that a crack may be generated in the U-shape portion A5 by repeating numbers of deformation.
A need thus exists for a pressure-sensing switch which improves the durability.
In light of the foregoing, the present invention provides a pressure sensing switch extended in an X-Y plane surface, the pressure sensing switch including at least a pressure detection member and a film for wrapping the pressure detection member, which includes at least a pair of first pressure sensing portions arranged in an X-direction and at least one connection portion provided between the first pressure sensing portions for connecting the first pressure sensing portions one another. The first connection portion includes a first straight portion extended in the X-direction and second straight portions formed by inverting both ends of the first straight portion. Each one end of the second straight portions is further inverted for connecting to each first pressure sensing portion.
According to another aspect of the present invention, a pressure sensing switch extended in an X-Y direction, the pressure sensing switch including at least a pressure detection member and a film for wrapping the pressure detection member, which includes at least a pair of pressure sensing portions, at least a pair of first pressure sensing band extended in an X-direction in the pressure sensing portions, and at least one first connection portion for connecting the pair of first pressure sensing bands. The first connection portion includes a first straight portion extended in the X-direction and second straight portions formed by inverting both ends of the first straight portion. The second straight portions are further inverted for connecting the first connection portion and the first pressure sensing bands.